Protractor.



N. 886,695. V u PATENTED MAY 5, i908.

J. GRENER.

PROTRAGTOR.

Hummm mi@ ma. 15, 1907. BBHBWED A1134, i908.

v .l a SHEETS-SHEET 1.

Winess, y venan No. 888,895. PATENTBD MAY 5, 1808,

y LA; GRENIER.

APPLUATIGN FILED FEB. 15, 190'7 BENEWED APE. 1, 190B. A 3 SHEETS-SHEET 2.

No. 886,695. PATENTED MAY 5, 1908.

J. A. GRENIER,

PROTRCTR.

APPLIOATIUN FILED FEB. l5, 1907. RENEWED APR. l, 1908.

S SHEETS-SHEET S.

Wz'nesses [ym/@mfom `following to be a full, clear,

Atrusses or .other structures.

A UNITED l JOSEPH "ARTHUR-Gann Nt. 886,695. y. Aspci'station Application mtdr'etttary i5,` 1967, settant.

To all whom 'it may concer/n: y y

Be it known that I, JOSEPH `ARTHUR GRENIER, a citizen of the UnitedtStates,`re siding at Beaver Falls, in the county o f Beaver and State of Pennsylvania, have invented certain new and useful Improvements in Protractors; and I do hereby declare the and eXactdescription of the invent-ion, such as will venable others skilled in the art to whichi't appe r tains to make and use the same. My inventlon relates to a mathematical devlce or contrlvance, commonly called protractor, and is designed for measuring thel functions and properties of angles; it is made 1n various forms,-namely, circular, semlcircular or rectangular.

The ob]ects of my mvention are,flrst:

to readily determine the trigonometrical 20 functions of angles, their measure in degrees and fractions thereof being known. Second; to readily determine the' measure 1n degrees and fractions thereof, of angles their trlgonometrlcal functions bemg known. Third:

Vto readily determine the stresses in members 'of roof and bridge trusses or other structures, and fourth: to readily determine the sizes and dimensions of the material to. be employed in the construction of roof and bridge I attain these objects by the instrument illustrated in the accompanying drawings and which I call a trigonograph. y

My invention consists of a bottom sheet graduated for'the purpose, a top transparent sheet also graduated for the purpose; these two sheets being connected by a pivot, so that the top sheet may be revolved upon the face of the bottom sheet; all as more clearly described hereafter in this specification. *l 7.

In the accompanying drawings, Figure 1 Arepresents a bottom sheet graduated, as dethe graduations on the bottom sheet,- and Fig. 5 represents, for the purpose of demonstration, a truss connection.

rnorrtric'roit of lvl-Letters l meansI of little vsee Fig. 3.

throughout the 'several viewshu The bottom Sheet A, rig. 1, it maaar bristol board-or any othen `material suitable for the purpose, havingl its face. graduated,

as follows :-rst, from the pivot point bl in the center, inches and fractions thereof,

or other denominations of measure, ,indicatedl upwards and downwards by horizontal'lines;

and correspondingV 4 ligures in vertical rotation.y Second, from' the saidpivot point b f..

in the center, inches and fractions thereof, or'

other denominations of measure', indicatedto'.

the right and to the left, by vertical lines and corresponding iigures'in horizontal rotation.

Third, on the circumferencey of a "circle, having forits center the said pivot ,point-bfi degrees and fractions thereof indicated by radial lines and corres onding figures. To the bottom sheet, 'A, Fig..` 1, at the ivot point b" is veryaccurately and solidfy attached by means of little prongs c, vthe The top sheet B, Fig. 2, is madeof transparent celluloid or any other .transparent material suitable for the purpose it is of'circular form, the diameter of which is a trifle less than the diameterof the lcircumference described on the bottom sheet A, Fig. 1,

and has for its center the said pivot point 6. The said top sheet is graduatedfthe same as, and correspondingly to the said bottom sheet, excepting the circle ofl degrees` whichis omitted on the said topvsheet.,y To the top sheet B, Fig. 2,*at the pivot point t is accurately and solidly attached by prongs "lt/ the pivot ff/n,

`The pivot bearing, Fig'. v3, consists yof two parts the pivot support ff andthe pivot ""Ml 'The support ff has'a thin circular 1li-ange p with .two or more pointed prongs c extendin out of the circumference of the ange. A ho low stock n formin part of" the support iff extends up the fu thickness of the bottom sheet HA. The diameter of the hollow part of the stock ra at'the top, is a trifle less than the diameter of the remainder -of the said hollow part. The pivot m has a knob r and a shaft s the pivot m has two or more pron s hfor the purpose of fastening it to t e top sheet "Bf7 The shaft s has its upper part turned to a diameter a trifle larger than' the diameter of the hollow part of the stock lowpart of the stock 'n, an .down to a looseness in the said hollow 'stock n the thickness of the top sheety B Where its diameter is'reduced to vthesame diameter as the top of the'hollow'part of the stock fn' the lower part of the shaft is turned'to aldiaineter`a trifle larger than the to ofthe holpoint. rIhus the -pivot fm is so constructed that its shaft s maybe forced in vand out'of the hollow stock n and when it is in, that it may 'turn-freely but without ivot.m and thesupport f are made v'of rass or any other materlal suitable for the purpose.

On the circumference of the top sheet Bf."

Fig. 2, a'small arc will contain a vernier scale k when particularlly iine work'is required.`

One example will su ce to demonstrate the manner in which my invention is' operated.

' In the truss connection, Fig. 5, in which the distan'ce L center to center of intersections of the member t and the angle of .o'bliquity of said member .t, 10 in 1-2, arev known, it is necessary to determine the dis-v tance 0, from intersection b of the membert to the end of said member t, at each end, order to ascertain the length of the material required to construct saidmember L It is also necessary tol determine the distance c vertically from the intersection line of .bottom chord b-fy tothe farthest rivet on plate e in line of member t, and the distance d horizontall from intersectional line of ost o to sai rivet, in order to ascertain t e size of the plate e. Heretofore the4 draftsman, to obtain these results, had to make a full size layout of the connection,

time, labor and vmateria -With my -invention, as shown in Fig. 4, I place the zero line' of the top sheet B so that it will intersect a point t twelve parts up .from and ten arts to the left ofthe pivot oint blwhich 1s the angle of Obliquity of t e member t,. then lI sketchl out temporarily, on the top sheet B the said truss connection, `as 'shown by dotted lines in Fi 4. Then I readon the line b-Jif the sai Vdistance o, two and one-fourth inches vertically the said distance The which reqluired considerable.

-a/ffour inches and horizontally the said .distance d three and ythree-eighths inches.

I alsofind that the line b-/ extended intersects the circle of degrees at thirty-nine degrees and forty-eight minutes, whichv is therefore the angle of Obliquity of the member t in degrees and minutes. Then the length of the member t is L-(o-l-o) and the plate ejafter adding the necessary edge distances must not be less than six and onefhalf inches long and six inches wide. If onthe line I2-1l I take a unitb-f1`. e uals one, I read horizontally the sine 1 -fw and vertically the cosine fw-JV of the angle of Obliquity of the member L If the stress in the member t is, say, Z1-fi, the stress in'the post v will be fw-b, and the stress in the bottom chord ZL-y will be fi-fw. It is not even necessary to sketch out the subject, as .shown by dotted lines in Fig. 4, vas it clan be mentally read on the instrument. No scaleis required these o erations, as the instrument is a scale in itse .The lines and figures on sheets A and B may be in black or colors. l

I am aware` that prior to my invention pro: tractors have been `made` with a circular sheet or frame having its circumference graduated in degrees'and minutes, and a cor-- responding sheet or framev having an index thereon and made to turn concentri'cally one on the other for the purpose of measuring angles. I therefore do not claim such a combination broadly; but

What I claim as my invention and desire to secure by Letters Patent is:

A protractor composed -of a graduated bottom sheet, a transparent top sheet graduf atedcorrespondinglyto said bottom sheetl and containing a vernier scale, a pivot sup.- port fastened to the center ofthe said bottom sheet, and a pivot made to turn in the said supcportxand fastened to the center, of the sai top sheet, all substantially as and' for the purpose described.

In testimony whereof, I affix my signature in presence of twowitnesses.

` JOSEPH ARTHUR GRENIER. Witnesses:

DEMrsnY L. Rnnnn, DEANORms CARR. 

